flash: implement 'flash'

Use our own escape sequence for the 'flash' terminfo entry.

Implemented by arming a timer FD and setting a boolean that indicates
we're currently "flashing".

The renderer draws a semi-transparent yellowish layer over the entire
window when "flashing" is active.

csi.c

@@ -5,6 +5,8 @@
 #include <unistd.h>
 #include <assert.h>
 
+#include <sys/timerfd.h>
+
 #if defined(_DEBUG)
  #include <stdio.h>
 #endif
@@ -573,6 +575,23 @@ csi_dispatch(struct terminal *term, uint8_t final)
                 break;
             }
 
+            case 1001: {
+                /* Our own private - flash */
+                unsigned duration_ms = vt_param_get(term, 1, 100);
+                LOG_WARN("FLASH for %ums", duration_ms);
+
+                struct itimerspec alarm = {
+                    .it_value = {.tv_sec = 0, .tv_nsec = duration_ms * 1000000},
+                };
+
+                if (timerfd_settime(term->flash_timer_fd, 0, &alarm, NULL) < 0)
+                    LOG_ERRNO("failed to arm flash timer");
+                else {
+                    term->flash_active = true;
+                }
+                break;
+            }
+
             default:
                 LOG_WARN("ignoring %s", csi_as_string(term, final));
                 break;

foot.info

@@ -49,7 +49,7 @@ foot+base|foot base fragment,
     ed=\E[J,
     el=\E[K,
     el1=\E[1K,
-    flash=\E[?5h$<100/>\E[?5l,
+    flash=\E[1001;100t,
     home=\E[H,
     hpa=\E[%i%p1%dG,
     ht=^I,

main.c

@@ -10,6 +10,8 @@
 #include <poll.h>
 #include <errno.h>
 
+#include <sys/timerfd.h>
+
 #include <freetype/tttables.h>
 #include <cairo-ft.h>
 #include <wayland-client.h>
@@ -325,6 +327,7 @@ main(int argc, char *const *argv)
         .keypad_keys_mode = KEYPAD_NUMERICAL,
         .auto_margin = true,
         .window_title_stack = tll_init(),
+        .flash_timer_fd = timerfd_create(CLOCK_BOOTTIME, TFD_CLOEXEC),
         .vt = {
             .state = 1,  /* STATE_GROUND */
             .attrs = {
@@ -681,6 +684,7 @@ main(int argc, char *const *argv)
             {.fd = wl_display_get_fd(term.wl.display), .events = POLLIN},
             {.fd = term.ptmx,                     .events = POLLIN},
             {.fd = term.kbd.repeat.pipe_read_fd,  .events = POLLIN},
+            {.fd = term.flash_timer_fd,           .events = POLLIN},
         };
 
         wl_display_flush(term.wl.display);
@@ -775,6 +779,23 @@ main(int argc, char *const *argv)
 
         if (fds[2].revents & POLLHUP)
             LOG_ERR("keyboard repeat handling thread died");
+
+        if (fds[3].revents & POLLIN) {
+            uint64_t expiration_count;
+            ssize_t ret = read(
+                term.flash_timer_fd, &expiration_count, sizeof(expiration_count));
+
+            if (ret < 0)
+                LOG_ERRNO("failed to read flash timer");
+            else
+                LOG_DBG("flash timer expired %llu times",
+                        (unsigned long long)expiration_count);
+
+            term.flash_active = false;
+            term_damage_view(&term);
+            if (term.frame_callback == NULL)
+                grid_render(&term);
+        }
     }
 
 out:
@@ -862,6 +883,9 @@ out:
             cairo_glyph_free(f->glyph_cache[j].glyphs);
     }
 
+    if (term.flash_timer_fd != -1)
+        close(term.flash_timer_fd);
+
     if (term.ptmx != -1)
         close(term.ptmx);
 

render.c

@@ -296,34 +296,40 @@ grid_render(struct terminal *term)
     struct buffer *buf = shm_get_buffer(term->wl.shm, term->width, term->height);
     cairo_set_operator(buf->cairo, CAIRO_OPERATOR_SOURCE);
 
+    if (term->flash_active)
+        term_damage_view(term);
+
     static struct buffer *last_buf = NULL;
-    if (last_buf != buf || false) {
-        if (last_buf != NULL) {
-            LOG_DBG("new buffer");
+    static bool last_flash = false;
 
-            /* Fill area outside the cell grid with the default background color */
-            int rmargin = term->cols * term->cell_width;
-            int bmargin = term->rows * term->cell_height;
-            int rmargin_width = term->width - rmargin;
-            int bmargin_height = term->height - bmargin;
+    /* If we resized the window, or is flashing, or just stopped flashing */
+    if (last_buf != buf || term->flash_active || last_flash) {
+        LOG_DBG("new buffer");
 
-            uint32_t _bg = !term->reverse ? term->colors.bg : term->colors.fg;
-            struct rgb bg = color_hex_to_rgb(_bg);
-            cairo_set_source_rgb(buf->cairo, bg.r, bg.g, bg.b);
+        /* Fill area outside the cell grid with the default background color */
+        int rmargin = term->cols * term->cell_width;
+        int bmargin = term->rows * term->cell_height;
+        int rmargin_width = term->width - rmargin;
+        int bmargin_height = term->height - bmargin;
 
-            cairo_rectangle(buf->cairo, rmargin, 0, rmargin_width, term->height);
-            cairo_rectangle(buf->cairo, 0, bmargin, term->width, bmargin_height);
-            cairo_fill(buf->cairo);
+        uint32_t _bg = !term->reverse ? term->colors.bg : term->colors.fg;
+        struct rgb bg = color_hex_to_rgb(_bg);
+        cairo_set_source_rgb(buf->cairo, bg.r, bg.g, bg.b);
 
-            wl_surface_damage_buffer(
-                term->wl.surface, rmargin, 0, rmargin_width, term->height);
-            wl_surface_damage_buffer(
-                term->wl.surface, 0, bmargin, term->width, bmargin_height);
+        cairo_rectangle(buf->cairo, rmargin, 0, rmargin_width, term->height);
+        cairo_rectangle(buf->cairo, 0, bmargin, term->width, bmargin_height);
+        cairo_fill(buf->cairo);
+
+        wl_surface_damage_buffer(
+            term->wl.surface, rmargin, 0, rmargin_width, term->height);
+        wl_surface_damage_buffer(
+            term->wl.surface, 0, bmargin, term->width, bmargin_height);
+
+        /* Force a full grid refresh */
+        term_damage_view(term);
 
-            /* Force a full grid refresh */
-            term_damage_all(term);
-        }
         last_buf = buf;
+        last_flash = term->flash_active;
     }
 
     bool all_clean = tll_length(term->grid->scroll_damage) == 0;
@@ -419,6 +425,16 @@ grid_render(struct terminal *term)
     if (gseq.count > 0)
         gseq_flush(term, buf);
 
+    if (term->flash_active) {
+        cairo_set_source_rgba(buf->cairo, 1.0, 1.0, 0.0, 0.5);
+        cairo_set_operator(buf->cairo, CAIRO_OPERATOR_OVER);
+        cairo_rectangle(buf->cairo, 0, 0, term->width, term->height);
+        cairo_fill(buf->cairo);
+
+        wl_surface_damage_buffer(
+            term->wl.surface, 0, 0, term->width, term->height);
+    }
+
     assert(term->grid->offset >= 0 && term->grid->offset < term->grid->num_rows);
     assert(term->grid->view >= 0 && term->grid->view < term->grid->num_rows);
 

terminal.h

@@ -243,6 +243,9 @@ struct terminal {
     char *window_title;
     tll(char *) window_title_stack;
 
+    bool flash_active;
+    int flash_timer_fd;
+
     struct vt vt;
     struct kbd kbd;